Residents within a 30-mile (50-kilometer) radius of the volcano were forced to evacuate the area, which includes Chaitén—the town nearest the volcano—as well as the Futaleufú Valley, a rural zone populated largely by small farmers. (See Chile map.)

The holdouts were mostly farmers who would not leave their livestock behind, the Associated Press reported.

Also on Thursday officials from Chile's agriculture ministry informed National Geographic News that an estimated 15,331 head of cattle, 12,828 sheep, and 957 horses have been targeted for evacuation.

"These statistics are dynamic and could change according to new events that we are monitoring from the ground and satellite images," said a ministry official who is not authorized to speak to the press.

On Wednesday teams of veterinarians were dispatched to the area to help ranchers struggling to save their livestock, according to Chile's agriculture minister, Marigen Hornkohl.

Hornkohl promised support for farmers, including debt cancellation, evacuation support, and feedstock and medical supplies, an official bulletin said.